The epidemic of Kaposi's sarcoma and acquired immunodeficiency syndrome (AIDS) has created a health hazard of major proportions for certain sectors of population. The seriousness and urgency of this problem are based on the following: 1) continuing increase in the number of reported cases and the high mortality rate of 40%; 2) these diseases are appearing beyond the confines of the population - subset originally affected and are manifesting among a cross-section of the general population; and 3) the etiologic agent(s) and the pathogenic mechanisms of these diseases are as yet unidentified, thereby creating alarm and uncertainty. The new epidemic of KS appeard in geographic clusters, as does the classical form, although the affected population is distinctly different. Examination of the available data suggests the involvement of life-style, environment, genetics and infectious agents as well as the common finding of profound immunodeficiency which is unique to the new epidemic. The proposed program has five inter-related aims and is designed to: 1) describe the epidemiology of the AIDS, based on the case-control method of inquiry, in terms of major risk factors and co-factors; 2) determine which of the involved factors best differentiate between the case and control groups; 3) determine, through the screening program with skin testing, the proportion of the population at risk affected by AIDS and identify cases of this syndrome at the early stage; 4) develop a mechanism for enlarging the scope of the screening effort; and 5) identify the factors responsible for progression of AIDS from the silent stage to the more severe manifestations. The overall objective of the project is to utilize case-control method of inquiry and DNCB skin testing for anergy screening to determine the magnitude of the problem of AIDS among population at risk, to identify characteristics which differentiate between cases and control groups and to diagnose cases at early stage of the disease, with an ultimate goal of a better understanding of the factors involved and pathogenic mechanisms of the syndrome and hopefully identification of the etiologic agent.